Field of the Invention
The present invention relates to a roll mount that is fixedly mounted to a vehicle body and supports behavior of a powertrain, and more particularly, to a roll mount using a magnetorheological fluid (MRF), which is capable of controlling properties thereof depending on a traveling condition of a vehicle by using the magnetorheological fluid having flow properties that vary as a magnetic field is formed.
Description of Related Art
In a passenger vehicle, a powertrain, which is configured by coupling an engine and a transmission, is generally mounted by a four-point mounting method (which supports behavior of the powertrain at four points) or by a three-point mounting method (which supports behavior of the powertrain at three points) depending on a size and an arrangement of the power train.
Meanwhile, high-performance vehicles, which are designed in a midship type (in which the powertrain is disposed at a center or at a rear side of a vehicle body) in order to distribute a weight of the vehicle in front and rear directions, adopt the four-point mounting method as illustrated in FIG. 1A so as to more securely support the behavior of the powertrain.
In the four-point mounting method, an engine mount 7 and a transmission (TM) mount 8 are disposed at both sides of a powertrain 6 to support a load, and roll mounts 1 are connected to a lower side of the powertrain 6 at front and rear sides of a drive shaft 9 that transmits rotational force of an engine to wheels, thereby supporting rolling motion of the powertrain 6.
That is, the engine mount 7 and the TM mount 8 are disposed at both sides of the powertrain 6, respectively, to support a load of the powertrain 6, and the roll mounts 1, which are attached at the lower side of the powertrain 6, are additionally connected with the powertrain 6, such that the roll mounts 1 share the functions of controlling displacement and attenuating vibration with the engine mount 7 and the TM mount 8.
As illustrated in FIG. 1B, the roll mount 1 in the related art has a structure in which a bracket 3 with a mounting portion 2 having a pipe shape is fixedly fastened to the vehicle body by bolting, and an insulator 5 made of an elastic material is mounted on the mounting portion 2. A core 4, which is coupled to the powertrain 6, is coupled at a center of the insulator 5, and recessed grooves 5a are formed at upper and lower sides of the core 4, respectively, to allow up and down vibration of the insulator 5 to more easily occur.
Meanwhile, as properties of the insulator 5 of the roll rod 1 are increased (as the insulator 5 becomes harder), traveling performance becomes better because a roll angle of the powertrain 6 is decreased. However, as properties of the insulator 5 are decreased (as the insulator 5 is greatly elastically deformed), noise, vibration, and harshness (NVH) performance is improved because the insulator 5 is advantageous in insulating vibration when the vehicle is idling.
Therefore, in the case of the high-performance vehicle with the structure in the related art, the properties of the insulator 5 are set while placing emphasis on the traveling performance rather than the NVH performance, and as a result, there is a problem in that the NVH performance deteriorates in inverse proportion to the traveling performance.
Therefore, there is a need for a roll mount capable of maintaining low properties thereof when the vehicle is idling, and increasing properties thereof according to a traveling condition when the vehicle starts moving or travels.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.